1. Field of the Invention
This invention relates to an aid used to practice the striking of a golf ball with a golf club.
In order to perfect the golf swing it is necessary to observe the direction and distance of the golf ball once it is struck. Ideally this observation is done at a driving range where the golfer is able to watch the entire flight of the ball, examining its trajectory, direction and distance. Often, however, the inconveniences (i.e. location, retrieval of golf balls, expense) associated with driving ranges prevent the golfer from using them. As such, golfers turn to portable golf practice devices. The primary advantage of the portable golf practice aids is that the devices can be used in a limited space. One disadvantage associated with the portable devices is that because the ball typically is held captive, by a netting or cord attachment to the ball, ball flight and ball direction are not as easily observed. Another disadvantage is that when the ball is attached to a cord, the flight, rotation and feel of the ball are compromised.
2. Description of the Prior Art
Various portable golf practice aids are disclosed in the prior art. One type of such aids includes an apparatus for striking a golf ball into a netting. The disadvantages of this type of device are that the ball must be retrieved from the netting each time it is struck, and it is difficult to examine the flight direction and distance of the ball.
Another such device includes a golf ball which is permanently attached to a rod, by a short cord or chain, which rotates upon striking the ball. Again the disadvantage to this type of device is that it is difficult to observe the ball flight distance and direction.
Another common portable device uses a tethered ball apparatus, where the ball is attached to a cord and the cord is fixed to the ground by attaching it to a stake or some other fixed object in the ground. Examples of this type of device are shown in U.S. Pat. Nos. 5,116,059 (Pelletier), 3,494,621 (Windall) and 5,560,604 (Watts). This type of practice device has several disadvantages associated with it. Firstly, a surface that is suitable for grounding a stake or other fixed object is required, thus making use of such a type of device indoors or on concrete rather difficult if not impossible. Secondly, if using a cord that is fixed to the ground, the cord itself must be highly durable in order to absorb the forces associated with striking a ball, while at the same time being light in weight in order to maximize the realism associated with the ball flight once struck. This has been difficult to achieve. Thirdly, the anchoring of the cord to the ground and the attachment to the ball are difficult to maintain due to the forces associated with striking the golf ball. The prior art discloses an attachment where the cord is secured to the ball by a single link. In such a single link attachment, the characteristics of composition and/or mass and/or shape of the golf ball may be significantly changed to permit the link to be joined to the golf ball. Another disadvantage to this type of attachment is that because the ball is secured to the cord, it is not allowed to spin freely, thus further diminishing the realism associated with ball flight and motion. In order to spread the force of the golf ball away from the connections at the stake and the ball, many of these tethered ball devices use an elastic or partially elastic cord. The safety hazards associated with using an elastic tethered cord are significant. When the ball is struck, the elastic cord to which the ball is attached extends to its maximum length at which point it rebounds to the original striking position or further at a high velocity, potentially causing danger to the golfer.
Other prior art, e.g. U.S. Pat. No. 5,560,604 (Watts) discloses an attachment mechanism where the cord is inserted through a hole in the center of the ball and is spliced to another part of the cord forming a loop. The advantage to this attachment mechanism over the balls which are attached at one point to the cord is that having the aperture extend through the center of the ball does not cause as rapid a deterioration and distortion of the ball as the single attachments. This patent, however, discloses an attachment that does not allow the ball to spin freely around the cord, thus lessening the realism associated with striking the ball.
Another invention, shown in U.S. Pat. No. 3,298,232 (Carboni) discloses a golf practice aid using a ball attached to a tethered cord which itself is attached to a heavy mass, consisting of a heavy block, anchoring block and trailing bar, which are not fixed to the ground. When struck, the ball flies to the end of the cord's length at which point the energy of the ball is transmitted to the heavy block apparatus, which is dragged slightly forward and left or right depending on the direction of the ball. The movement of the block and trailing bar gives the golfer an indication of the approximate distance and direction the ball flies. The trailing bar's lateral movement is limited by a fixed guide, thus limiting the assessment of lateral ball flight. Full analysis of the golf swing requires an aid which reliably assesses a wide range of lateral movement of the golf ball.